This invention starts from an adjusting device, especially from a combined window lifter and central door locking installation in motor vehicles, comprising a reversible electric motor and a mechanism which transmits a movement of the electric motor and which, between two end positions, is adjustable by the electric motor into two oppposed directions.
Such an installation is known from the German laid open print No. 28 54 713. In addition to some embodiments in which the mechanism is adjusted in the one direction by an electric motor and in the other direction by a spring element which has been prestressed during the previous movement this specification also shows an embodiment in which the movement of the electric motor in the one direction and in the other direction is the direct cause for a displacement of the mechanism. For this purpose a rod of the mechanism is suspended in a sheet metal part on which the electric motor is mounted and, when the window pane also adjustable by the motor is blocked, the sheet metal part is swivelled together with the electric motor. Both in the first mentioned embodiments and in the last one the mechanism, which transmits a movement of the electric motor to the lock of the door, cannot be manually adjusted from one stable end position into the other. When the mechanism is directly coupled with the electric motor in both adjusting directions any attempt of a manual displacement is blocked by the fact that the electric motor is self-locking. When, on the other hand, the mechanism is moved in the one direction by the electric motor and in the other direction by a prestressed spring element a manual displacement in the direction in which, normally, the electric motor is active would immediately be followed by a resetting through the spring element when the external force is no longer applied. In this case the vehicle could eventually be manually locked in a complicated way in that the locking button, which is part of the door locking installation, in its depressed position normally corresponding to a locked vehicle door, is once again locked by additional measures. This is rather complicated and, moreover, also unreliable, because a supposedly locked door can still be unlocked, if one forgot to lock the button additionally. Furthermore a vehicle door can only be manually unlocked, if it was manually locked before. If it were locked by the electric motor a manual unlocking is blocked by the self-locking electric motor.
The German laid open print No. 28 07 673 shows several adjusting devices including a mechanism which is adjustable by an electric motor between two end positions and transmits a movement of the electric motor to the lock of a vehicle door. The mechanism is fitted with a device which permits manually to adjust parts of the electric motor, when the electric motor is at standstill. Thereby the electric motor of the adjusting devices always rotates in the same direction. Thus the devices for manual displacement are designed in such a way that they can predominantly be used with such electric motors and cannot be used with reversible electric motors.
It is the objective of the invention to develop an adjusting device including the features of the present invention in such a way that due to its design it can be operated more easily. Above all it has to be possible also manually to adjust the adjusting element on which the mechanism transmits the movement of the electric motor. This is to be achieved in a manner as simple as possible and without disturbing the other functions of the adjusting device.